A 29-mRNA host-response classifier identifies bacterial infections following liver transplantation – a pilot study

Purpose Infections are common complications in patients following liver transplantation (LTX). The early diagnosis and prognosis of these infections is an unmet medical need even when using routine biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT). Therefore, new approaches are necessary. Methods In a prospective, observational pilot study, we monitored 30 consecutive patients daily between days 0 and 13 following LTX using the 29-mRNA host classifier IMX-BVN-3b that determine the likelihood of bacterial infections and viral infections. True infection status was determined using clinical adjudication. Results were compared to the accuracy of CRP and PCT for patients with and without bacterial infection due to clinical adjudication. Results Clinical adjudication confirmed bacterial infections in 10 and fungal infections in 2 patients. 20 patients stayed non-infected until day 13 post-LTX. IMX-BVN-3b bacterial scores were increased directly following LTX and decreased until day four in all patients. Bacterial IMX-BVN-3b scores detected bacterial infections in 9 out of 10 patients. PCT concentrations did not differ between patients with or without bacterial, whereas CRP was elevated in all patients with significantly higher levels in patients with bacterial infections. Conclusion The 29-mRNA host classifier IMX-BVN-3b identified bacterial infections in post-LTX patients and did so earlier than routine biomarkers. While our pilot study holds promise future studies will determine whether these classifiers may help to identify post-LTX infections earlier and improve patient management. Clinical trial notation German Clinical Trials Register: DRKS00023236, Registered 07 October 2020, https://drks.de/search/en/trial/DRKS00023236 Supplementary Information The online version contains supplementary material available at 10.1007/s00423-024-03373-1.

(a) Procalcitonin (PCT) was measured in patients following liver transplantation.Patients were divided according to the occurrence of a proven bacterial infection within the first 14 days following LTX.PCT levels are presented for unobtrusive patients (white box) and patients with bacterial infection (grey box).Plasma samples were collected immediately following liver transplantation (d0), and the days afterwards until day 13 as indicated.Data in the box plots are given as the median, 25 th percentile, and 75 th percentile with the 10 th as well as 90 th percentile at the end of the whiskers.Concerning symbolism and higher orders of significance: p < 0.05: *, Mann-Whitney U Test.
(b) C-reactive protein (CRP) was measured in patients following liver transplantation.Patients were divided according to the occurrence of a proven bacterial infection within the first 14 days following LTX.CRP levels are presented for unobtrusive patients (white box) and patients with bacterial infection (grey box).Plasma samples were collected immediately following liver transplantation (d0), and the days afterwards until day 13 as indicated.Dpre indicates the last measurement the day before LTX.Data in the box plots are given as the median, 25 th percentile, and 75 th percentile with the 10 th as well as 90 th percentile at the end of the whiskers.Concerning symbolism and higher orders of significance: p < 0.05: *, Mann-Whitney U Test.
(c) White blood cell counts were measured in patients following liver transplantation.Patients were divided according to the occurrence of a proven bacterial infection within the first 14 days following LTX.

Timepoints
✱ were collected immediately following liver transplantation (d0), and the days afterwards until day 13 as indicated.Dpre indicates the last measurement the day before LTX.
Data in the box plots are given as the median, 25 th percentile, and 75 th percentile with the 10 th as well as 90 th percentile at the end of the whiskers.Concerning symbolism and higher orders of significance: p < 0.05: *, Mann-Whitney U Test.
Supplementary Figure 3: Bacterial IMX-BVN-3b scores in patients following liver transplantation adjusted to the timepoint of the bacterial infection.Viral IMX-BVN-3b scores were measured in patients following liver transplantation.Data in are given as the median with 95% confidence interval (CI).Performance characteristics of the A: IMX-BVN-3b.B: procalcitonin (PCT) and C: C-reactive protein (CRP).When segmented into the results interpretation bands among patients with a proven bacterial infection.PCT and CRP were segmented into interpretation bands using cutoffs established in other studies [2][3][4][5][6].Formulars are described in [7].Abreviations: n.a.: not applicable

Supplementary Figure 4 :
Bacterial IMX-BVN-3b scores were measured in patients following liver transplantation.Bacterial IMX-BVN-3b-scores are presented for unobtrusive patients as green line combined with light grey area and light green points for each single course and for patients with bacterial infections as red line combined with a dark grey area and orange points for each single course.In patients with a bacterial infection, new timepoints were created by matching them to the first time of bacterial infection, whereas the control group without bacterial infection was created by matching them in an age-and sex-related manner to the same timepoints of patients with a bacterial infection.The following virtual timepoints were created: the first measurement two days before the first bacterial infection (preV-2), the first measurement two days before the first bacterial infection (preV-1), the plasma level at the time of bacterial infection (V0) and the next measured plasma levels on the days afterwards (V1-V4).Data are presented as median with 95% Confidence interval as borders of the areas and single courses for each patient.(b)Receiver operator characteristics (ROC)-analysis for bacterial IMX-BVN-3b scores in bacterial infected vs. uninfected patients regarding the indicated virtual timepoints as described above.Abbreviations: AUC, area under the curve; CI, confidence interval Viral IMX-BVN-3b scores in patients following liver transplantation.

Table 1 :
Accuracy of IMX-BVN-3b, procalcitonin and C-reactive protein for the diagnosis of bacterial infections in 30 patients from day 0 to 13 after enrollment Legend: Performance of Bacterial IMX-BVN-3b after applying previously established cutoffs to segment scores into clinically actionable results interpretation bands according to[1].